The invention relates to a belt retractor for a vehicle seat belt comprising a frame provided with plural blocking teeth, a belt reel being pivoted in the frame and having a blocking tooth system, and comprising a control mechanism by which the belt reel can be moved from a home position in which it can freely rotate in the frame to a blocking position in which its blocking tooth system engages in the blocking teeth of the frame.
In this type of belt retractor the belt reel is displaced, when it is to be locked, relative to the frame so that the tooth system arranged at the same engages in the blocking teeth provided at the frame. For this purpose, a control mechanism is provided which ensures that the tooth system of the belt reel is controlled to take the correct position in the blocking teeth of the frame so that engagement of the tooth system in the blocking teeth is produced before high loads are acting on the belt reel.
The control mechanism includes the control lever usually provided with an internal tooth system in which a control pawl arranged at an end face of the belt reel can engage. The control pawl can be released in a way either sensitive to the belt webbing or sensitive to the vehicle so that it engages in the internal tooth system and fixedly couples the belt reel to the control lever. When in this state a tensile force is exerted by the webbing on the belt reel, this results in the fact that the control lever together with the belt reel pivots about the pivot point at which the control lever is arranged at the frame and the belt reel is controlled to engage in the locking teeth at the frame. The arrangement of the teeth of the internal tooth system at the control lever relative to the blocking teeth ensures that the belt reel is basically guided with its tooth system in the correct position into the blocking teeth so that the tooth crests of the tooth system of the belt reel are prevented from impacting on the tooth crests of the blocking teeth.
It has not been known so far to provide a belt retractor of this type with a child lock as it is called, viz. a possibility of locking the belt reel so that the webbing can be wound onto the same but cannot be unwound from the same any more. This function is useful, for instance, for fixing child' safety seats on a vehicle seat. Child lock systems are basically generally known, to be sure (cf. e.g. EP 1 209 047 A1), but they are used only with belt retractors in which the belt reel is received in the frame of the belt retractor with a fixed axis of rotation.